1. Field of the Invention
The present invention relates generally to a braking system for an elevator and more particularly to the system to control the deceleration of an elevator during an emergency braking condition.
2. Description of the Background Art
Modern elevator systems are among the safest modes of travel and normally provide smooth and comfortable rides for its passengers. Furthermore, computerized control system currently available provide the cars with a gentle landing at the selected floors so as to avoid the uncomfortable feeling of sudden deceleration and jerkiness.
Various devices have been configured to control the motor drive of the elevator so that the movement of the car is smooth and comfortable for the passengers. U.S. Pat. No. 4,570,755 shows a computer which controls the movement of an elevator car during the final several inches of travel approaching a selected floor. Similarly, U.S. Pat. No. 4,220,221 shows a system for controlling the velocity of the vehicle so that it is stopped smoothly while being aligned with a desired floor. Likewise, U.S. Pat. No. 3,743,055 controls the acceleration and deceleration of an elevator car as it moves between floors.
These and other systems provide for gentle landings by controlling the motor when the elevator is in the normal operational mode. However, during an emergency situation, emergency braking systems are utilized to stop the elevator car. These emergencies may be due to a power failure, a broken safety chain or some other sensed